Belar FMHD-1, Руководство оператора

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FMHD-1 Operator’s Manual
BELAR ELECTRONICS LABORATORY, INC. Page 33
ANL Pwr
The power existing in the analog FM carrier.
LSB Pwr
The total power in the hybrid IBOC lower digital sideband.
USB Pwr
The total power in the hybrid IBOC upper digital sideband.
HD Pwr
The total power in both hybrid IBOC digital sidebands.
Ratio
The ratio of the total power in the IBOC digital sidebands (HD Pwr) to the power in the
analog FM carrier (ANL Pwr). (This is the ratio regulated by the Federal Communications
Commission.)
When the FMHD-1 is properly installed, the
Measurements
feature provides quick verification of the
correct relative IBOC HD™ power levels. Note that activating the RF Spectrum Measurement function
establishes a fixed set of display parameters for the RF Spectrum Screen.
8
List of Definitions
µV, UV
Equivalently, microvolt(s). A microvolt is the root-mean-square voltage of an RF signal, in millionths of
a volt. One microvolt is the equivalent of –108.8dBm on a 75
Ω system, or –107dBm on a 50Ω system. A
“mVrms”, or millivolt RMS, is 1000 times a microvolt. A millivolt RMS is –
48.8dBm on a 75Ω system,
or –
47dBm on a 50Ω system.
AES/EBU
Refers to the Audio Engineering Society/European Broadcast Union standard for transmission of two
channels of digital program signals over matched transmission lines. In the case of the
FMHD-1 , the
designation refers to AES-3ID, a variation of the standard for transmission over 75
Ω coaxial cables.
Average (AVG)
For DC signals, the voltage value of a signal integrated over a specified interval of time. In the case of AC
signals, the absolute value of a signal voltage integrated over a specified time interval. Because of the
importance of maintaining modulation levels in broadcasting, the
FMHD-1 indicates average modulation
as the averaged value of the peak modulation readings collected over a user-set time interval.
Common-Line Facilities
In FM hybrid IBOC transmitter facilities, this refers to the situation where the high-power analog and
digital components of the hybrid signal are fed to the antenna system via a single transmission line. The
analog and digital portions of the transmitted signal may be combined in a high-level RF combiner. The
analog and digital signals may also be combined at low-levels or in a split-level system, and then
amplified. Finally, the hybrid signal combination may be synthesized directly and then amplified to the
required power as one signal.
Composite
This is short for “composite signal.”
The composite signal is the combination of component signals that FM-modulate the carrier in a modern
FM broadcast signal: the DSB-encoded FM-stereo audio signal, the stereo pilot, possibly the RBDS
(RDS), and one or more SCA signals. It may refer to the signal combination as it enters the FM exciter,